//Trigonometry.java
//basic unit circle value of trig functions

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.border.*;
import java.util.*;
import java.text.*;

public class Trigonometry extends JApplet implements ActionListener {     

    double r, theta, x, y, tan, arc;
    JPanel controlPanel;
    JLabel rLabel, thetaLabel, xLabel, yLabel, tanLabel, arcLabel;
    JTextField rTextField, thetaTextField, xTextField, yTextField, tanTextField, arcTextField;
    
    int endX, endY;  //so mouseListener has access
    int rLen;
    int midX, midY;
    DecimalFormat d4, d2, i1;
    
    public void init() {
	String input;
	d4 = new DecimalFormat ("0.0000");
	d2 = new DecimalFormat ("0.00");
	i1 = new DecimalFormat ("0.000");
	
	Container container = getContentPane();
	container.setLayout( new BorderLayout() ); 

	controlPanel = new JPanel();
	controlPanel.setLayout(new FlowLayout());
	controlPanel.setBackground(Color.MAGENTA);
	controlPanel.setBorder(BorderFactory.createEtchedBorder(EtchedBorder.RAISED));
	container.add(controlPanel,BorderLayout.NORTH);

	
	rLabel = new JLabel( "r" );
	controlPanel.add( rLabel );
	r = 1.0;
	rTextField = new JTextField(""+d2.format(r),4);   
	rTextField.setHorizontalAlignment(JTextField.RIGHT);
	rTextField.addActionListener( this );
	controlPanel.add( rTextField );

	thetaLabel = new JLabel( "ANGLE \u0398\u00B0" );
	controlPanel.add( thetaLabel );
	thetaTextField = new JTextField("30.0",4);
	thetaTextField.setBackground(Color.GREEN);
	theta = Double.parseDouble(thetaTextField.getText());
	thetaTextField.setHorizontalAlignment(JTextField.RIGHT);
	thetaTextField.addActionListener( this );
	controlPanel.add( thetaTextField );
 			
/*	rLabel = new JLabel( "  LENGTHS: radius" );
	controlPanel.add( rLabel );
	rTextField = new JTextField("1.0",4);
	r = Double.parseDouble(rTextField.getText());
	rTextField.setBackground(new Color(200,200,255));
	//rTextField.setForeground(Color.WHITE);
	rTextField.setHorizontalAlignment(JTextField.RIGHT);
	rTextField.addActionListener( this );
	controlPanel.add( rTextField );
*/	
	xLabel = new JLabel( "x =r cos \u0398" );
	controlPanel.add( xLabel );
	x = r * Math.cos(Math.toRadians(theta));
	xTextField = new JTextField(""+d2.format(x),4);
	xTextField.setBackground(Color.CYAN);
	xTextField.setHorizontalAlignment(JTextField.RIGHT);
	xTextField.addActionListener( this );
	controlPanel.add( xTextField );

	yLabel = new JLabel( "y =r sin \u0398" );
	controlPanel.add( yLabel );
	y = r * Math.sin(Math.toRadians(theta));
	yTextField = new JTextField(""+d2.format(y),4);
	yTextField.setBackground(Color.YELLOW);
	yTextField.setHorizontalAlignment(JTextField.RIGHT);
	yTextField.addActionListener( this );
	controlPanel.add( yTextField );

	tanLabel = new JLabel( "tan =y/x=slope=sin\u0398/cos\u0398" );
	controlPanel.add( tanLabel );
	tan = y / x;
	tanTextField = new JTextField(""+d2.format(tan),4);
	tanTextField.setBackground(Color.BLUE);
	tanTextField.setHorizontalAlignment(JTextField.RIGHT);
	tanTextField.addActionListener( this );
	controlPanel.add( tanTextField );

	arcLabel = new JLabel( "arc" );
	controlPanel.add( arcLabel );
	arc = arcLength(r,theta);
	arcTextField = new JTextField(""+d4.format(arc),4);
	arcTextField.setBackground(Color.PINK);
	arcTextField.setHorizontalAlignment(JTextField.RIGHT);
	arcTextField.addActionListener( this );
	controlPanel.add( arcTextField );
/*
	sectorAreaLabel = new JLabel( "  AREAS: sector" );
	controlPanel.add( sectorAreaLabel );
	sectorArea = sectorArea(r,a);
	sectorAreaTextField = new JTextField(""+d4.format(sectorArea),4);
	sectorAreaTextField.setBackground(Color.PINK);
	//sectorAreaTextField.setForeground(Color.WHITE);
	sectorAreaTextField.setHorizontalAlignment(JTextField.RIGHT);
	sectorAreaTextField.addActionListener( this );
	controlPanel.add( sectorAreaTextField );	
		
	triangleAreaLabel = new JLabel( "- triangle" );
	controlPanel.add( triangleAreaLabel );
	triangleArea = triangleArea(r,a);
	triangleAreaTextField = new JTextField(""+d4.format(triangleArea),4);
	triangleAreaTextField.setBackground(Color.PINK);
	triangleAreaTextField.setHorizontalAlignment(JTextField.RIGHT);
	triangleAreaTextField.addActionListener( this );
	controlPanel.add( triangleAreaTextField );	
		
	segmentAreaLabel = new JLabel( "= segment" );
	controlPanel.add( segmentAreaLabel );
	segmentArea = sectorArea - triangleArea;
	segmentAreaTextField = new JTextField(""+d4.format(segmentArea),4);
	segmentAreaTextField.setBackground(Color.PINK);
	segmentAreaTextField.setHorizontalAlignment(JTextField.RIGHT);
	//segmentAreaTextField.setEditable(false);
	segmentAreaTextField.addActionListener( this );
	controlPanel.add( segmentAreaTextField );			
*/	
	rLen = getHeight()/3;  //mouseListener needs
	midX = getWidth()/2;
	midY = getHeight()/2;
		
	
	rTextField.setText("1.0");
	rTextField.postActionEvent();  //fires listener
	
  	//incantation that responds to mouse move events:
	addMouseMotionListener(
	       new MouseMotionAdapter() {
		   public void mouseDragged( MouseEvent event) {
	               int px = event.getX();
	               int py = event.getY();
	               double x=-999, y=-999;  //inits to fake out compiler for showStatus
	               
		       double mouseDistance = distanceFormula(px,py, endX,endY);
		       
		       if (mouseDistance < 50) { //within 50 of endPoint
		           if (theta < 180) {  //left right: px change
	               	       /*if (px < endX)   //leftward
	               	           //scale px to actual x, then a=acos(x/r)
	               	           x = (double)endX/rLen - (double)px/rLen;
	               	       else
	               	       	   x = (double)px/rLen - (double)endX/rLen;
	               	       	   */
	               	       x = (double)(px-midX)/rLen;
	               	       if (x <= r && x >= -r)   //avoid going under?? at 0
	               	           theta = Math.toDegrees(Math.acos(x/r));
	               	       //if (a < 0)  // ?? nope
	               	       	 //  a = 0;
		           }
		           else if (theta > 180) {  //left right: opp. of upper half circle
	               	       x = (double)(midX-px)/rLen;
	               	       if (x <= r && x >= -r)   //avoid going under?? at 360
	               	           theta = 180 + Math.toDegrees(Math.acos(x/r));
		               
		           }
		           else { //a==180  ??
		               if (py != midY) {  //has to be at least one pixel above or below
		                   y = (double)(py-midY)/rLen;
		                   theta = 180 + Math.toDegrees(Math.asin(y/r));
		               }
		           }
	               	   //showStatus("("+px+","+(getHeight()-py)+")  x="+x+"  y="+y+"  a="+a);
		           thetaTextField.setText(""+d2.format(theta));
	                   thetaTextField.postActionEvent(); 
		       }   	
		   } 
	       }
	 );    
   }


    public void setTextFields( double r, double theta, double x, double y, double tan, double arc) {
       rTextField.setText(""+d2.format(r)); 
       thetaTextField.setText(""+d2.format(theta));   	
       xTextField.setText(""+d2.format(x));
       yTextField.setText(""+d2.format(y));
       tanTextField.setText(""+d2.format(tan));
       arcTextField.setText(""+d2.format(arc));
    }

    public void actionPerformed( ActionEvent event ) {
    	try {
	    double thetaTry = Double.parseDouble(thetaTextField.getText());
	    if (thetaTry<0 || thetaTry>360) {
	      	JOptionPane.showMessageDialog(null,
					  "theta angle must be between 0 and 360 degrees",
					  "Trigonometry: Invalid ANGLE DEGREES input",
					  JOptionPane.ERROR_MESSAGE);
	        return;
	    }

	    double rTry = Double.parseDouble(rTextField.getText());
	    if (rTry<0) {
	      	JOptionPane.showMessageDialog(null,
					  "radius must be greater than 0",
					  "Trigonometry: Invalid RADIUS input",
					  JOptionPane.ERROR_MESSAGE);
	        return;
	    }
/*	    double xTry = Double.parseDouble(xTextField.getText());
	    if (xTry<r*Math.cos(Math.toRadians(theta)) || xTry>2*r) {
	      	JOptionPane.showMessageDialog(null,
					  "x must be between 0 and diameter",
					  "Trigonometry: Invalid X input",
					  JOptionPane.ERROR_MESSAGE);
	        return;
	    }
	    double yTry = Double.parseDouble(yTextField.getText());
	    if (yTry<0 || yTry>r) {
	      	JOptionPane.showMessageDialog(null,
					  "y must be between 0 and radius",
					  "Trigonometry: Invalid Y input",
					  JOptionPane.ERROR_MESSAGE);
	        return;
	    }
*/	
	    double tanTry = Double.parseDouble(tanTextField.getText()); //check it's a number

	    double arcTry = Double.parseDouble(arcTextField.getText());
	    if (arcTry<0)   {    // || arcTry>2*Math.PI+.001) {
	      	JOptionPane.showMessageDialog(null,
					  "arc must be between 0 and 2\u03C0 radians",
					  "Trigonometry: Invalid ARC LENGTH input",
					  JOptionPane.ERROR_MESSAGE);
	        return;
	    }
    
	}
	catch (NumberFormatException e) {
	    JOptionPane.showMessageDialog(null,
					  "all values must be numbers",
					  "Trigonometry: Invalid input",
					  JOptionPane.ERROR_MESSAGE);
	    return;
	}
	
    	if ( event.getSource() == thetaTextField ) {
	    theta = Double.parseDouble(thetaTextField.getText());
	    //rad = Math.toRadians(theta);
	    arc = arcLength(r,theta);
	    //sectorArea = sectorArea(r,a);
	    x = r * Math.cos(Math.toRadians(theta));
	    y = r * Math.sin(Math.toRadians(theta));
	    tan = y / x;
	    //if (theta <= 180) {
	        //c = chordLength(r,a);
	        //h = heightLength(r,c);
	        //triangleArea = triangleArea(r,a);
	        //segmentArea = sectorArea - triangleArea;
	        setTextFields(r,theta,x,y,tan,arc);
	   // }
	 /*   else {
	    	c = 0;
	    	h = 0;
	    	triangleArea = 0;
	    	segmentArea = 0;
	        setTextFields(r,theta,x,y);
	    }
	   */
	    repaint();    
	}
	else if ( event.getSource() == rTextField ) {
	    r = Double.parseDouble(rTextField.getText());
	    thetaTextField.postActionEvent();  //fires its listener
	    //setTextFields(r,theta,x,y,tan,arc);
	    //repaint();    		
	}		
	else if ( event.getSource() == xTextField ) {
	    x = Double.parseDouble(xTextField.getText());
	    theta = Math.toDegrees(Math.acos(x));
	    thetaTextField.setText(""+d2.format(theta)); 
	    thetaTextField.postActionEvent();  //fires its listener
	}
	else if ( event.getSource() == yTextField ) {
	    y = Double.parseDouble(yTextField.getText());
	    theta = Math.toDegrees(Math.asin(y)); 
	    thetaTextField.setText(""+d2.format(theta)); 
	    thetaTextField.postActionEvent();  //fires its listener
	}
	else if ( event.getSource() == tanTextField ) {
	    tan = Double.parseDouble(tanTextField.getText());
	    theta = Math.toDegrees(Math.atan(tan)); 
	    thetaTextField.setText(""+d2.format(theta)); 
	    thetaTextField.postActionEvent();  //fires its listener
	}
	else if ( event.getSource() == arcTextField ) {
	    arc = Double.parseDouble(arcTextField.getText());
	    theta = thetaFromArcLength(r, arc);
	    thetaTextField.setText(""+d2.format(theta)); 
	    thetaTextField.postActionEvent();  //fires its listener
	}

    }
    
    public void paint (Graphics g) {
	super.paint( g );   //erase 
        g.setFont( new Font( "SansSerif", Font.BOLD, 12 ) );

	g.drawString("Set any parameter ",5,50);
	g.drawString("OR  Drag endpoint of radius around circle",5,70);

	int w = getWidth();
	int h = getHeight();
	//int midX = w/2;
	//int midY = h/2;
	//int rLen = h/3;
	
	//g.drawOval(midX-rLen, midY-rLen, 2*rLen, 2*rLen);
	g.drawLine(0,midY, w ,midY);
	g.drawLine(midX,0, midX,h);
	g.drawArc(midX-rLen,midY-rLen,2*rLen,2*rLen, (int)theta,360-(int)theta);	
	g.fillRect(midX-1,midY-1, 2,2);
	g.drawString("(0,0)",midX-5,midY+10);
	
	//g.setColor(Color.BLUE);
	//g.drawLine(midX,midY, midX+rLen ,midY);
	g.drawString("("+r+",0)",midX+rLen+1,midY+10);


	//int endX, endY;
	endX = (int)(Math.cos(Math.toRadians(theta)) * rLen + midX);
	endY = h - (int)(Math.sin(Math.toRadians(theta)) * rLen + midY);
	g.setColor(Color.CYAN);
	g.drawLine(midX,midY, endX ,midY);
	g.setColor(Color.YELLOW);
	g.drawLine(endX,midY, endX ,endY);

	g.setColor(Color.BLUE);
	g.drawLine(midX,midY, endX,endY);
	if (theta<=90 || theta>=270) {
	    g.setColor(Color.CYAN);
	    g.drawString("("+d2.format(Math.cos(Math.toRadians(theta))*r)+",",
	          endX,endY);
	    g.setColor(Color.YELLOW);
	    g.drawString(""+d2.format(Math.sin(Math.toRadians(theta))*r)+")",
	          endX+30,endY);
	}
	else {
	    g.setColor(Color.CYAN);
	    g.drawString("("+d2.format(Math.cos(Math.toRadians(theta))*r)+",",
	          endX-rLen/2,endY);
	    g.setColor(Color.YELLOW);
	    g.drawString(""+d2.format(Math.sin(Math.toRadians(theta))*r)+")",
	          endX-rLen/2+30,endY);
	}
		
	//arc
	g.setColor(Color.PINK);
	g.drawArc(midX-rLen,midY-rLen,2*rLen,2*rLen, 0,(int)theta);	

	//theta
	g.setColor(Color.GREEN);
	g.drawArc(midX-25,midY-25,50,50, 0,(int)theta);	
	g.drawString("\u0398",midX+30,midY-20);
		
	//chord
/*	if (c != 0) {
	    g.setColor(Color.CYAN);
	    g.drawLine(endX,endY, midX+rLen,midY);
	
	    //midpoint on chord
	    int chordMidX= (endX+(midX+rLen)) / 2;
	    int chordMidY= (endY+midY) / 2;
	    //height h
	    g.setColor(Color.YELLOW);
	    g.drawLine(midX,midY, chordMidX,chordMidY);
	}
*/

	//data on screen	
        g.setColor( Color.BLACK );
	g.drawString("area="+d2.format(Math.PI*r*r),w-200,45); 	                             
	g.drawString("circumference="+d2.format(2*Math.PI*r),w-200,60);
/*	if (theta < 180) {
            g.setColor( Color.CYAN);
	    g.drawString("base midpoint ("+d2.format((r+Math.cos(Math.toRadians(theta))*r)/2)+
	  	         ","+d2.format(Math.sin(Math.toRadians(theta))*r/2)+")",w-200,75);
	}
*/	

    }
	
 /*   public double chordLength(double r, double a) {
    	return Math.sqrt(2*r*r - 2*r*r*Math.cos(Math.toRadians(a)));
    }	
   */ 	
    //height of isocelese triangle
/*    public double heightLength(double r, double c) {
    	return Math.sqrt(r*r - c*c/4);
    }	
*/
   public double arcLength(double r, double theta) {
    	return 2*Math.PI*r * (theta/360);
    }
   public double thetaFromArcLength(double r, double arc) {
    	return (arc*360)/(2*Math.PI*r);
    }
    
  /*  public double triangleArea(double r, double a) {
    	return r*r/2 * Math.sin(Math.toRadians(a));
    }	
    */
    
/*    public double sectorArea(double r, double a) {
    	return Math.PI*r*r * (a/360);
    }
*/
    public double distanceFormula (double x1, double y1, double x2, double y2){
    	return Math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
    }
    
    //use Newton's method to solve g=PIr^2*Alpha/360 - r^2/2*sin(Alpha2PI/360)
    //letting x=Alpha2PI/360   K=2g/r^2.   g is segmentArea
    // K=x-sin(x)
    //f(x)=K-x+sin(x)   f'(x)=-1+cos(x)
    //x(n+1)=x(n) - (K-xn+sin(xn))/(-1+cos(xn)
    //Thanks to Andy Won for this math.
    //returns alpha in degrees.   alpha=2PI/360 x
    public double NewtonsAlpha(double r, double g) {
    	double xn, xn1=1, fx;  //fakeout compiler
    	double K=2*g/(r*r);
    	xn = 1;   //initial value.  crucial choice.  implies alpha=57 (1 rad) OK?
    	fx = K - xn + Math.sin(xn);
    	int iterations=1;
    	while (Math.abs(fx) > .00001 && iterations<200) {   //no more than 200 loops?   .00001 OK?
    	    xn1 = xn - fx/(-1+Math.cos(xn));
    	    fx = K - xn1 + Math.sin(xn1);
    	    xn = xn1;
    	    iterations++;
    	}
    	//seems to work for any segmentArea between 0 and semicircleArea (alpha=180)
    	showStatus("iterations"+iterations);
    	return 180/Math.PI * xn1;
    	
    }
}